The present invention relates to air conditioning systems. More particularly, the invention relates to an improved evaporative type air conditioning system.
Most air conditioning systems use vapor-compression or absorption refrigeration cycles. Although such air conditioning systems are effective at cooling, they use a great deal of energy.
Evaporative type air conditioning systems cool air, liquids, or other mediums with much less energy than vapor-compression and absorption refrigeration systems. Evaporative cooling works by employing water's large enthalpy of vaporization. The temperature of air, especially when dry, can be dropped significantly through phase transition of water from a liquid to a vapor. In dry climates, evaporative cooling also has the added benefit of adding humidity to the conditioned air.
A typical evaporative air conditioner has a water pump that applies water to one or more evaporative cooling pads and a fan or blower that blows ambient air over the pads. The air evaporates the water in the pads and thus removes heat from the air through evaporative cooling. The cool moist air is then delivered to a building or other conditioned space through vents and/or duct work.
Although evaporative air conditioners use less energy than vapor-compression/absorption type systems, they suffer from several distinct disadvantages. For example, evaporative air conditioners often introduce too much humidity into a building, which can be uncomfortable and cause walls, doors, and furniture to swell and metal components to corrode.
Evaporative air conditioners also require large volumes of air to be introduced into a conditioned space, thus requiring equal amounts of air inside the conditioned space to be vented out. This creates drafts and introduces dust and other particles into the space. Air passed over the evaporative pads can be recirculated from inside the building to reduce the required amount of outside air, but air is ideally only allowed to pass through the evaporative pads once because the air loses its cooling effect as it becomes saturated with water (dry air evaporates water more quickly than damp air).
Evaporative cooling can also introduce odors into a conditioned space because the evaporative pads often promote the growth of mold, mildew, and/or bacteria. The fans necessary for the constant exchange of air within the conditioned space can also create excessive fan noise and vibrations.
Indirect evaporative air conditioner systems solve some of the above-described problems by utilizing heat exchangers so that the cooled, moist air never comes into direct contact with the conditioned space. However, known indirect evaporative systems require a great deal of water and are not efficient nor practical in areas of high humidity.